Re: Scanner gamma for profiling [was: Re: maclife.de]
Re: Scanner gamma for profiling [was: Re: maclife.de]
- Subject: Re: Scanner gamma for profiling [was: Re: maclife.de]
- From: Uli Zappe <email@hidden>
- Date: Sat, 6 Sep 2008 14:03:59 +0200
Am 06.09.2008 um 09:01 schrieb Marco Ugolini:
In a message dated 8/4/08 10:16 PM, Uli Zappe wrote:
The most remarkable test result for me was that the profile quality
depends very much on the scanner gamma used. This is true for all
profiling software, but to a different degree.
[...]
This reminds me of an exchange I had with the late Bruce Fraser on
the ColorSync forum in early 2006.
Yes, Bruce [et al.] also describes this procedure in "Real World Color
Management", which inspired me to check the gamma in my test. So the
test owes this insight to Bruce and his co-authors, and confirms its
importance.
SilverFast, BTW, also allows you to set gamma to any value between 1.0
and 3.0 (even in 0.01 incements, IIRC!), so that the many scanners
supported by SilverFast gain this ability.
The problem is that though it's basically easy, this test is
cumbersome (you need ColorLab and need to know how to use it, and
there's a lot of repetitive work), so not too many users will perform
it. As a consequence, they will probably "blindly" choose a gamma that
actually decides (in an extreme case like SilverFast's own profiling
option) whether they are using a very good or very bad profiling
software.
It would help if the profiling software would at least automatically
perform the evaluation Bruce describes after the creation of each
profile and display its result, but none does. MonacoProfiler and
SilverFast's profiling option do report evaluation results at the end,
but both seem to use a "simpler" procedure than Bruce describes and
end up with unrealistically low and meaningless delta E values.
Bye
Uli
________________________________________________________
Uli Zappe, Solmsstraße 5, D-65189 Wiesbaden, Germany
http://www.ritual.org
Fon: +49-700-ULIZAPPE
Fax: +49-700-ZAPPEFAX
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